This proposal outlines a research plan to examine the risk behaviors of at-risk groups for HIV infection in the Atlanta Metropolitan Statistical Area (MSA) as a part of the Centers for Disease Control and Prevention's National HIV Behavioral Surveillance (NHBS) System. Similar research is being conducted in other participating cities across the country. The research team will conduct rotating cycles of data collection from the following high-risk groups;men who have sex with men (MSM), high-risk heterosexuals (HET) and intravenous drug-users (IDU) in addition to the proposed recruitment of male-to-female transgendered women (MTF). As part of this endeavor, a total of 1650 adults will be recruited over a maximum of five cycles of data collection and activities that are planned to take place from January 2011 through December 2015. The data collected will assist researchers in understanding the factors that facilitate the risk of HIV among each of these at-risk populations. Each cycle of this project will include two stages: the formative research stage and the behavioral surveillance data collection phase. Data collection will occur using a standardized questionnaire aimed at gathering demographic information, sexual/drug-using risk information as well has HIV testing information. Sample methodologies during the data collection phase will be unique to the particular data collection cycle. The IDU, HET, and MTF cycles will utilize respondent driven sampling (RDS), while the MSM cycle will utilize venue-based time-space sampling (VBS). Given the recent CDC ranking for the Atlanta MSA as 2nd among the national MSA/Divisions for 2008 newly diagnosed HIV infection, behavioral risk information is a critical asset to reducing new infections in the area. The main objective of this project is to assess and monitor trends in HIV risk, testing behaviors and access to preventive services among these populations at highest risk for infection. Following data collection, NHBS researchers will collaborate with local organizations and agencies to provide stakeholders with findings relevant to meeting prevention goals of reducing HIV infection in the MSA among these high-risk populations.